The present invention relates to a lithographic method and a carrier substrate.
A lithographic apparatus is a machine that applies a desired pattern onto a target portion of a substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In that circumstance, a patterning device, which is alternatively referred to as a mask or a reticle, may be used to generate a circuit pattern corresponding to an individual layer of the IC, and this pattern can be imaged onto a target portion (e.g. comprising part of, one or several dies) on a substrate (e.g. a silicon wafer) that has a layer of radiation-sensitive material (resist). In general, a single substrate will contain a network of adjacent target portions that are successively exposed. Known lithographic apparatuses include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion in one go, and so-called scanners, in which each target portion is irradiated by scanning the pattern through the beam in a given direction (the “scanning”-direction) while synchronously scanning the substrate parallel or anti-parallel to this direction.
In a conventional lithographic apparatus, a substrate onto which a pattern is to be projected is held on a substrate table by applying a vacuum through the substrate table onto a lowermost surface of the substrate. Once the pattern has been applied to the substrate, the vacuum is released to allow the substrate to be removed from the substrate table and replaced with a subsequent substrate to be patterned. In some instances, the shape or stricture of a substrate may be such that a vacuum cannot be used to hold the substrate on the substrate table.
It is desirable to provide a lithographic method and a lithographic carrier substrate which overcome or mitigate one or more problems of the prior art, whether identified herein or elsewhere.